Charles e



(No Model.)

0. E. SGRIBNER.

APPARATUS FOR TELEPHONE SWITGHBOARDfi 'No. 597,787. Patented, Jan. 25,1898.

m5 mums PETERS no. PHOTO LYTHQ..WASH5NGTON, 0 c.

UNITED STATES PATENT Erica CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS,ASSIGNOR TO THE lVESTE-RN ELECTRIC COMPANY, OF SAME PLACE.

APPARATUS FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 597,787, dated January25, 1898.

Application filed December 18,1896. Serial No. 616,128 (No model.)

This invention concerns means for auto-v matically controlling linesignals of telephone lines in switchboards through the agency of thestation apparatus of the line and for causing the edacement of thesignal in the establishment of the required connection with the line.

Prior to this invention signaling appliances have been used consistingof subsidiary signals in the switchboard associated with the lines andrelays controlling the line-signals responsive to cu. rren ts in thelines determined in the use of the telephones at the substations, and ithas been proposed to cause the eiiacement of the line-signal or toreturn it to its normal inert condition in the operators act of makingconnection with the line in response to an initial call through theagency of a second relay excited incidentally through suitable circuitschanged in that act and acting to shift the circuits of the subsidiarysig nal in a suitable way to effect the desired end. The presentinvention relates to organizations of this type; and it consists in aspecific arrangement and construction of the relay connected with theline and controlling the signal to display it and of the relay excitedin making connection with the line and controlling the same signal toefiace it, as follows: The magnets of the two relays act upon anarmature common to both. The relay in the line when excited brings thisarmature into contact with an anvil and thus closes a local circuitthrough the subsidiary line-si na-l. The other or local relaybecomesexcited when connection is made with the line in reply to this signaland retracts the armature in opposition to the force of the line-relay,thus breaking the circuit through the subsidiary signal and renderingthat appliance inert. This local magnet is placed in a local batterycircuit terminating in normally-separated contact-pieces in thespring-jacks of the line, which become connected together by a pluginserted in the spring-jack.

The invention is illustrated in the accompanying drawing, wherein twosubstations are represented with line conductors led to signaling andswitching appliances in the switchboard, a single pair of plugs andtheir plug-circuit being shown in the switchboard in position foruniting the two lines.

The apparatus at the substation is of wellknown type, the apparatusbeing adapted to close the line-circuit as to continuous cur rents whilethe telephone is in use. The line conductors are connected in theswitchboard at the central office with the line-contacts of spring-jacksa and a and are extended through windings of the relay b to the poles ofa battery 0, which is common to the diiferent lines of the exchange. Thespring-jacks are assumed to be upon difterent sections of V a multipleswitchboard. The armature b of the relay b, with its contact 6 controlsa local circuit 3, which includes a signal-lamp d, associated withspring-jack a, together with a source of current. The armature Z7 isalso within the field of a magnet b which is included in a portion 4 ofthe local circuit which terminates in thimbles or contact-rings e of thespring-jacks of the line. The compleinentary portion of the localcircuit is a conductor 5, which terminates in opposing contact-pieces cin the spring-jacks. This conductor includes a battery f. These parts 6and e are designed to register with and be crossed together by aseparate contact-piece in the plug which is used with them. The type ofspring-jack is well known in the art of telephony.

The magnet 11 is constructed to have a greater eifect upon the armatureb than the magnet b, and hence when excited acts to retract the armatureto its normal position, in which it is separated from itsswitch-contact, and thus to open the local circuit 3.

The connecting-plugs g and g have each a pair of line-contacts h and h,which register with the springs e and e of the spring-jack, and a sleeve71 which crosses together the IOU contact-pieces e and e of thespring-jack. The tips h of the plugs are united by a conductor 6 and therings h by another conductor 7. These conductors constitute theplugcircuit. The usual calling-key t'is interposed in them in positionto interrupt the connection between the two plugs and to loop agenerator 7c of calling-current into circuit with the plug g, and theusual operators listeningkey Z is furnished to bring the operatorstelephone m into bridge of the plug-circuit. In a permanently-closedbridge 8 of this circuit the source of current a is contained, togetherwith windings of impedance-coils 0. the windings, o, is included betweenone pole of the battery and the conductor 7. Two other windings, 0 and 0are interposed between the battery and conductor 6. They are normallyconnected in multiple, but their.

multiple connection is controlled by switchcontacts Z and Z of theoperators listeningkey for purposes of testing, as will be hereinafterdescribed. That pole of battery 0 which is connected with conductor 6 isalso grounded.

The sleeves 72 of the plugsg and g constitute the terminals or groundedconductors9 and 10, respectively, whose continuity is controlled by theswitch-contacts ofrelays p and The magnet of the former of these isincludedin conductor 7 of the plugcircuitbetween the plug 9 and thepoint of connection of battery 0 with the plug-circuit, and that of thelatter is similarly included in conductor 7 between plug g and thebattery. Hence each of the relayswill respond to current created by thebattery in the plug-circuitand through the conductors of one only of thelinesthat one with which the plug corresponding to the relay isconnected. These conductors 9 and 10 include supervisory lampsignals qand g, respectively, each of which is associatedwith the plugformingtheterminal of the conductor which includes it.

The operationof these signals is as follows: The removal of thereceiving-telephone from its switch atasubstation permits the battery 6to create a current in the line-circuitvand through the windings ofmagnet b, whereby the magnet is caused to close the local circuit,

3, including the subsidiary signal-lamp cl. The lighting of this lampcalls the attention of the operator, who responds to the signal byinserting plug g into the answering-jack a. This'act creates anextension of the line conductors 1 2 through the conductors 6 and 7 ofthe plug-circuit, and thence to the oper-v ators telephone, the key Zhaving beenv depressed, so that the operator is broughtinto.communicationwith the subscriber. -It,als0 closes the local circuit 4 5by crossingtogether the contact-pieces e and e of the springjack,whereby the armature b of the relay is retracted and the signal-lamp dis extin guished. At the same time the electrical condition oftest-rings e of the line isalteredto indicate the busy condition of theline to an operator at a distant switchboard, the rings "office.

nection required,the operator makes the usual test of the line calledfor by applying the tip being raised to a difference of potential fromthe earth corresponding to the electromotive force of battery f. Theconductor 9, terminating in the sleeve 71 of the plug, also becomesconnected with this battery f in condition to permit the illumination ofsupervisory lamp q when the break in the conductor shall be closed byrelay-p. It will be observed that this relay is now excited by currentflowing from battery 0 through conductor 7, line conductors 1 and 2, andconductor 6 of the plug circuit, returning to battery 0 at the centralHaving learned the order for the conh of plug 9 to the test-ring e ofthe springjack of the required line. Obviously if no connection existswith that line no test-signal will be received, since the circuit whichis completed from earth through winding 0 conductor 7 to the tip of theplug, and conductor t to earth includes no source of current. If,however, a connection with the line be already in existence, there willbe a branch from the rings 6 through the plug, whereby the connectionhas been made to the contactpiece 6" and thence through battery f toearth. Then at each application of the test-plug to the test-ring acurrent will flow through the winding 0 of the impedance-coil to earth,

whereby a current will be induced in winding '0 which will circulate inthe circuit including the operators telephone and will make an audiblesignal therein.

It will be noted that the conductor 6. of the plug-circuit forms aportion of the returncircuit of 'current'rt'rom batteryc through theline, and. hence its electrical condition will be altered by variouschanges in the conditions of the line and its utility as a portion of acircuitvfor testing the electrical condition of other lineswould beimpaired, The function ofcontacts Z and Z and of windings 0 and o is, toseparate the portion of conductor 6 lead ing to the tip of the plug fromthe remainder of the plug-circuit, preserving only an inductiveconnection between them. Then no change in the conditions of the circuitexinto the spring-jack brings the spring-jacks of-that line intocondition to test busy subsequently. It. also causes the magnetb of thatline .to holdthe armature Z2 against any force which the othermagnet bmay exert and brings the battery f into circuit with conductor 10,including the supervisory signal q".

\Vhen the- Since no circuit as yet exists through the subscribers lineto the station called, the telephone at that station being still on itsswitchhook, the relay 2) is inert and permits the closing of the breakin conductor 10. Hence the supervisory lamp q is lighted and remains inthat condition until the response of the subscriber called permits thebattery 0 to create a current in the line.

While both supervisory lamps q and q remain dark, the operator mayassume that the subscribers are in conversation. When both becomelighted, this may be taken as indicating a signal for disconnection,after which the plugs may be removed from the springjacks and theappliances returned to their normal condition.

My invention is defined in the following claims: I

1. The combination with a telephone-line and means for determining theflow of current in the line during the use of the telephone, of a magnetresponsive to current in the line, an armature therefor, a secondarysignal, and circuits including the secondary signal controlled byswitchcontacts operated by the said armature, a second electromagnetadapted to retract the armature, a circuit includin g said secondmagnet, and circuits closed to excite the said magnet in the act ofmaking connection with the line, as described.

2. The combination with a telephone-line and means at the stationthereof determining the flow of current in the line during the use ofthe telephone, of a magnet in the line, an armature for the magnet andswitch-contacts therefor closed when the armature is attracted, asecondary signal and a local circuit including the signal controlled bythe switchcontacts, a second magnet acting on the same armature andadapted to retract it, a local circuit including the latter magnet, aspringjack for the line and a plug therefor, and normally-separatedswitch -contacts crossed together by the plug in the spring-jackcompleting the last-mentioned local circuit, as described.

In witness whereof I hereunto subscribe my name this 14th day ofNovember, A. D; 1896.

CHARLES E. SCRIBNER.

Witnesses:

ELLA EDLER, Duncan E, WILLETT,

